1. Field of the Invention
The present invention relates to a method for fabricating a semiconductor. More particularly, the present invention relates to a wet cleaning process and a method for fabricating a semiconductor device using the same.
2. Description of Related Art
Lithography process can be used for patterning various material layers or performing certain processes, such as ion implantation process, in a selected area, and which is a very important step in the fabricating process of semiconductor devices. According to a typical lithography process, a photoresist layer is first coated over a material layer. Some parts of the photoresist layer are then selectively irradiated during an exposure process. After that, parts of the photoresist layer are removed with developer so as to form a photoresist pattern. Those exposed parts with decomposition are removed by the developer if the photoresist layer is positive photoresist, and those unexposed parts without crosslink are removed by the developer if the photoresist layer is negative photoresist. After the photoresist pattern is formed, subsequent dielectric layer etching, metal layer etching, or ion implantation process etc can be performed with the photoresist pattern as a mask. The photoresist layer has to be removed by dry cleaning or wet cleaning after the subsequent etching or ion implantation process is completed. Usually, oxygen plasma is adopted in dry cleaning, and any organic solution or various acidic solutions can be used in wet cleaning. Thereafter, a cleaning process is performed to remove residual photoresist layer or impurities on the surface of the substrate.
Metal micro-corrosion may be caused, which is commonly known as pitting, while patterning a metal layer with foregoing conventional lithography or etching techniques, or if the metal layer is exposed while etching other insulation layers, especially when the material of the metal layer is aluminum or Al—Cu alloy.
A method for fabricating a semiconductor device is disclosed in U.S. Pat. No. 5,175,124, wherein carbonated water is used for rinsing a substrate after a photoresist layer is removed with an organic solution in order to reduce metal micro-corrosion.
In addition, a method for cleaning a semiconductor wafer is disclosed in U.S. Pat. No. 5,336,371, wherein metal micro-corrosion is reduced by introducing CO2 into a rinsing tank and overflowing the water.
Even though the problem of metal micro-corrosion can be eased by the methods disclosed in foregoing two patents, which cannot be resolved.